1. Technical Field of the Invention
The present invention relates to an oily composition and a process for producing the composition. More particularly, the present invention pertains to an oily composition excellent in storage stability and a process for producing the composition. The oily composition of the present invention may be used in the fields of foods, feeds, cosmetics, medicines, agricultural chemicals, machines and other various industrial fields, because of its excellent storage stability.
2. Prior Art
A water-soluble effective substance and/or a water-dispersible effective substance (hereinafter referred to as "aqueous effective substance") may be dispersed in an oil by directly adding the aqueous effective substance to the oil containing an emulsifying agent dissolved therein and mixing them. However, this process does not permit easy preparation of any uniform and stable dispersion of such an aqueous effective substance in an oil phase and does not ensure any effect of masking the taste of the aqueous effective substance. This is because the dispersion prepared by the method entrains coagulation and/or precipitation of the effective substance. In general, there has widely been adopted a method comprising the step of mixing and emulsifying a solution of an aqueous effective substance in an aqueous phase with an oil phase to thus give a water-in-oil type emulsified composition. As such water-in-oil (or W/O) type emulsified compositions whose aqueous phase contains certain substances, there have been proposed, for instance, a W/O type emulsion containing an antioxidant hardly soluble in oils and fats or a synergist [Japanese Patent Publication for Opposition Purpose (hereinafter referred to as "J. P. KOKOKU") No. Hei 4-64638], a W/O type lipophilic antioxidant containing a water-soluble antioxidant substance emulsified therein [Japanese Patent Un-Examined Published Application (hereinafter referred to as "J. P. KOKAI") No. Sho 63-135483], and a W/O type emulsified composition containing an acidic substance and/or a salt thereof (J. P. KOKAI No. Hei 6-343400).
However, any W/O type emulsified composition has not yet been developed, which can sufficiently, satisfactorily be applied to various applications in the foregoing industrial fields because the foregoing W/O type emulsified composition does not undergo any separation immediately after the preparation, but the composition causes the separation of the aqueous phase or the oiling off phenomenon during storage thereof due to the action of salts and acidic substances coexisting in the aqueous phase. In addition, a large quantity of water is present in the aqueous phase and this becomes a cause of hygienic problems such as decomposition and/or putrefaction of the aqueous effective substances and the growth of mold. Moreover, the W/O type emulsion never ensures a sufficient effect of masking the taste of the aqueous effective substances.